Among small-sized portable information processing apparatuses, such as a portable telephone set or a personal digital assistant, there are those provided with jog dials, as uniaxially controlled user interface devices, for improving one-hand tractability or simplifying the operating sequence.
For example, an operating menu for an equipment employing the jog dial, such as a portable telephone set, enables extremely simple menu operations, such as decision making operation, brought about by rotation and thrusting of the jog dial.
On the other hand, in an operating system (OS) for a personal computer (PC) or a personal digital assistant (PDA), typified by Windows95 (registered trademark) or Window98 (registered trademark) manufactured by Microsoft Company, USA, there is a menu interface traced by a random hierarchical structure termed ‘menu’. There is also an interface which is not the menu and which is comprised of tree and list views, in a transverse layout, as a basic interface of a file system. The ‘Explorer Window’ of the Windows manufactured by Microsoft Inc., USA, is of this type of the interface. By these means, it is possible to specify the current position in a tree structure or to directly revert to an optional hierarchical layer.
Meanwhile, if, in the above-mentioned operating menu, provided with the jog dial, the menu itself has a hierarchical structure, it is not possible to represent a particular position of the tree structure, such that a user finds it difficult to locate the position in the menu in the course of control. Additionally, when tracing back through hierarchical layers, it is only possible to return to the top menu or to the directly previous hierarchical layer, meaning only insufficient operating flexibility that can be offered to the user.
Moreover, in the above-mentioned operating system (OS), there are a menu interface traced by a random hierarchical structure termed ‘menu’ and an interface comprised of a horizontal array of tree or list view. These interfaces, however, may not be said to be optimum as an interface for a vertically elongated casing for a hand-held portable telephone set, or as an interface for a portable equipment that is in need of a vertically elongated display panel, since these interfaces necessarily use a display of a certain transverse width due to their structural constraints.